mcs: fix tls setting for microservices (#9344)

[ti-chi-bot]

This is an automated cherry-pick of #9344

What problem does this PR solve?

Issue Number: Close #9367

What is changed and how does it work?

Check List

Tests

• Unit test
• Manual test

This PR has been validated by operator.

Release note

None.

[ti-chi-bot]

@rleungx This PR has conflicts, I have hold it.
Please resolve them or ask others to resolve them, then comment /unhold to remove the hold label.

[ti-chi-bot]

@ti-chi-bot: ## If you want to know how to resolve it, please read the guide in TiDB Dev Guide.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.82%. Comparing base (0d0a253) to head (50afffc).
⚠️ Report is 11 commits behind head on release-8.5.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-8.5   #10005      +/-   ##
===============================================
+ Coverage        77.74%   77.82%   +0.08%     
===============================================
  Files              467      468       +1     
  Lines            62474    63144     +670     
===============================================
+ Hits             48570    49142     +572     
- Misses           10315    10387      +72     
- Partials          3589     3615      +26     

Flag	Coverage Δ
unittests	77.82% <85.71%> (+0.08%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[rleungx]

/hold cancel

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-12-10 01:45:56.72163169 +0000 UTC m=+1005501.535409262: ☑️ agreed by bufferflies.
• 2025-12-10 05:16:02.046252403 +0000 UTC m=+1018106.860029975: ☑️ agreed by JmPotato.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bufferflies, JmPotato, niubell

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [JmPotato,bufferflies]
• client/tlsutil/OWNERS [niubell]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment